In the video and photos below, a Shaolin monk is practicing chi kung. There are two very famous kinds of chi kung at the Shaolin temple: Yi-Jin Jing (muscle/tendon changing sutra) and Si-sue Jing (marrow washing sutra). The monk below is practicing Si-sue Jing.

To practice Si-sue Jing, you need to hang a weight from the root of the penis. You have to start with 3-5 pounds and after a year, some can hang as much as 300 pounds. Through hanging this weight, along with breathing exercises, it is believed that one can massage one's internal organs and balance one's endocrine system to promote good health. Danny practiced this kind of Chi Kung more than 20 years ago in Taiwan. For more on Danny's experience with this practice, you can read his blog article: My Experience Of Si-Sue Jing Qi Gong.

CAUTION: Below are some graphic illustrations and video of Shaolin monks performing hard chi kung. Do not try this without a qualified instructor (and maybe not even then! ;-)